webapi中的自定义路由约束

Custom Route Constraints

You can create custom route constraints by implementing the IHttpRouteConstraint interface. For example, the following constraint restricts a parameter to a non-zero integer value.



public class NonZeroConstraint : IHttpRouteConstraint

{

    public bool Match(HttpRequestMessage request, IHttpRoute route, string parameterName,

        IDictionary<string, object> values, HttpRouteDirection routeDirection)

    {

        object value;

        if (values.TryGetValue(parameterName, out value) && value != null)

        {

            long longValue;

            if (value is long)

            {

                longValue = (long)value;

                return longValue != 0;

            }

            string valueString = Convert.ToString(value, CultureInfo.InvariantCulture);

            if (Int64.TryParse(valueString, NumberStyles.Integer,

                CultureInfo.InvariantCulture, out longValue))

            {

                return longValue != 0;

            }

        }

        return false;

    }

}

The following code shows how to register the constraint:



public static class WebApiConfig

{

    public static void Register(HttpConfiguration config)

    {

        var constraintResolver = new DefaultInlineConstraintResolver();

        constraintResolver.ConstraintMap.Add("nonzero", typeof(NonZeroConstraint));

        config.MapHttpAttributeRoutes(constraintResolver);

    }

}

Now you can apply the constraint in your routes:



[Route("{id:nonzero}")]

public HttpResponseMessage GetNonZero(int id) { ... }

You can also replace the entire DefaultInlineConstraintResolver class by implementing the IInlineConstraintResolver interface. Doing so will replace all of the built-in constraints, unless your implementation of IInlineConstraintResolver specifically adds them.

巴特西

webapi中的自定义路由约束

Custom Route Constraints

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